Drive transmitting apparatus and image forming apparatus

ABSTRACT

When viewed in an axial direction, a pair of circumferential ends and a notched portion of a cylindrical shaft are at different positions in a circumferential direction, and a first central angle of a first imaginary arc which connects the pair of circumferential ends and a first force receiving portion nearest to the pair of circumferential ends in an opposite direction to a direction, in which a force is received, from the pair of circumferential ends to the first force receiving portion in the opposite direction is smaller than a second central angle of a second imaginary arc, which connects the pair of circumferential ends and a second force receiving portion nearest to the pair of circumferential ends in the direction, in which the force is received, from the pair of circumferential ends to the second force receiving portion in the direction in which the force is received.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a driving force transmitting mechanismin an image forming apparatus.

Description of the Related Art

Conventionally, a metallic solid shaft has been used for many shaft-likedrive transmitting members such as various roller shafts used in imageforming apparatuses such as copiers and printers. In contrast, the useof a hollow-structure cylindrical shaft (a metal plate cylindricalshaft) which is a metal plate formed in a cylindrical shape as a hollowshaft (a tubular shaft) in place of a solid shaft is being proposed forthe purposes of reducing weight and lowering costs such as material costand machining cost. However, compared to a metallic solid shaft, a metalplate cylindrical shaft having a seam at which end surfaces of a metalplate formed in a cylindrical shape come together tends to have lowertorsional rigidity, and there is a concern that rotation with highaccuracy cannot be performed. In addition, there is a concern that, whenloads due to drive transmission and the like is applied to the metalplate cylindrical shaft, the respective end surfaces of the seam portionmay deviate in a radial direction and an axial direction of thecylindrical shaft or the end surfaces may separate from each other towiden the seam, thereby causing a further decline in torsional strength.

In consideration thereof, in Japanese Patent Application Laid-open No.2006-289496, by providing a protruded shape and a recessed shape to eachend surface of a seam of metal plate end surfaces and having theprotruded shape and the recessed shape fit each other, a deviation and aseparation of the respective end surfaces of the seam in an axialdirection are suppressed and torsional rigidity is improved.

SUMMARY OF THE INVENTION

Japanese Patent Application Laid-open No. 2006-289496 discloses aconfiguration in which a width of an end surface in a protrudingdirection of a protruded shape and a width of an end surface in arecessing direction of a recessed shape provided on each end surface ofa seam are wider than a width of a base. Although this configuration iseffective in suppressing a deviation and a separation of the respectiveend surfaces of the seam, an end of a protruded portion of the protrudedshape cannot be inserted from a base side of the recessed shape.Therefore, when forming a cylindrical shape by a bending process of ametal plate cylindrical shaft, special consideration is required toensure that the protruded shape and the recessed shape smoothly fit eachother.

Meanwhile, Japanese Patent Application Laid-open No. 2013-164163discloses a configuration in which an angle between an end surface and aside surface in a protruding direction of a protruded shape and an anglebetween an end surface and a side surface in a recessing direction of arecessed shape provided on each end surface of a seam are set at anapproximately right angle. In addition, it is also described that theangles may be formed in obtuse angles in order to enable the protrudedshape and the recessed shape to fit each other more readily during pressworking. However, in such cases, although a deviation in an axialdirection of the respective end surfaces of the seam can be suppressedby a load applied to a metal plate cylindrical shaft due to drivetransmission and the like, there is still a concern that the protrudedshape and the recessed shape having been fitted to each other and therespective end surfaces may separate and the seam may open.

An object of the present invention is to provide a technique forsuppressing, with a simple configuration, a decline in torsionalstrength of a cylindrical shaft which transmits a driving force byrotation.

In order to achieve the object described above, a drive transmittingapparatus according to the present invention includes:

a first member;

a second member that drives due to a driving force of the first member;and

a cylindrical shaft that rotates in order to transmit the driving forceof the first member to the second member, the cylindrical shaftincluding a pair of circumferential ends that oppose or abut with eachother in a circumferential direction from one end to another end in anaxial direction as a seam and a notched portion that is recessed in theaxial direction on an approximately annular end surface at an end in theaxial direction, and the cylindrical shaft receiving a force in thecircumferential direction at the notched portion, wherein

when viewed in the axial direction,

the pair of circumferential ends and the notched portion are atdifferent positions in the circumferential direction.

In order to achieve the object described above, a drive transmittingapparatus according to the present invention includes:

a first member;

a second member that drives due to a driving force of the first member;and

a cylindrical shaft that rotates in order to transmit the driving forceof the first member to the second member, the cylindrical shaftincluding a pair of circumferential ends that oppose or abut with eachother in a circumferential direction from one end to another end in anaxial direction as a seam, and a notched portion that is recessed in theaxial direction on an approximately annular end surface at an end in theaxial direction, and the cylindrical shaft engaging with the firstmember in the notched portion and receiving the driving force of thefirst member in the circumferential direction, wherein

when viewed in the axial direction,

the pair of circumferential ends and the notched portion are atdifferent positions in the circumferential direction.

In order to achieve the object described above, a drive transmittingapparatus according to the present invention includes:

a first member that drives;

a second member that drives due to a driving force of the first member;and

a cylindrical shaft that rotates in order to transmit the driving forceof the first member to the second member, the cylindrical shaftincluding a pair of circumferential ends that oppose or abut with eachother in a circumferential direction from one end to another end in anaxial direction as a seam, and a notched portion that is recessed in theaxial direction on an approximately annular end surface at an end in theaxial direction, and the cylindrical shaft engaging with the secondmember in the notched portion and causing the driving force to act onthe second member in the circumferential direction, wherein

when viewed in the axial direction,

the pair of circumferential ends and the notched portion are atdifferent positions in the circumferential direction,

the notched portion includes, as force applying portions that cause thedriving force to act on the second member, a first force applyingportion that is nearest to the pair of circumferential ends in arotation direction of the cylindrical shaft and a second force applyingportion that is nearest to the pair of circumferential ends in anopposite direction to the rotation direction, and

when a first central angle denotes a central angle of an imaginary arc,which connects the pair of circumferential ends and the first forceapplying portion in the rotation direction from the pair ofcircumferential ends to the first force applying portion, and which hasas a center thereof the rotational center, and

when a second central angle denotes a central angle of an imaginary arc,which connects the pair of circumferential ends and the second forceapplying portion in the opposite direction from the pair ofcircumferential ends to the second force applying portion, and which hasas a center thereof the rotational center,

the first central angle is smaller than the second central angle.

In order to achieve the object described above, an image formingapparatus according to the present invention includes:

the drive transmitting apparatus; and

an image forming portion that forms an image on a recording material byusing a driving force transmitted by the drive transmitting apparatus.

According to the present invention, a decline in torsional strength of acylindrical shaft which transmits a driving force by rotation can besuppressed with a simple configuration.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example of an image forming apparatusaccording to an embodiment of the present invention;

FIG. 2 is a sectional schematic view of an example of an image formingapparatus according to an embodiment of the present invention;

FIG. 3 is a perspective view showing an example of an intermediatetransfer belt unit according to the present invention;

FIG. 4 is a perspective view showing a configuration of a driver rollerand a belt drive transmitting portion;

FIG. 5 is a schematic diagram showing a fabrication process of a metalplate cylindrical shaft and an apparatus configuration of amanufacturing apparatus;

FIG. 6 is a schematic diagram showing a shape of a metal plate afterpunching;

FIGS. 7A to 7D are schematic diagrams showing a bending process of ametal plate cylindrical shaft;

FIGS. 8A and 8B are diagrams showing a final shape of a metal platecylindrical shaft according to a first embodiment;

FIGS. 9A and 9B are diagrams showing another shape of a metal platecylindrical shaft;

FIG. 10 is a diagram showing a configuration of a belt drivetransmitting portion;

FIG. 11 is a sectional view showing a configuration of a driveinput-side coupling according to the first embodiment;

FIG. 12 is a sectional view taken along D-D of a drive-side couplingaccording to the first embodiment;

FIG. 13 is a sectional view taken along B-B of the drive-side couplingaccording to the first embodiment;

FIG. 14 is a sectional view showing a positional relationship between adrive receiving surface and a seam of the metal plate cylindrical shaftaccording to the first embodiment;

FIGS. 15A to 15C are diagrams showing a positional relationship betweena drive receiving surface and a seam of a metal plate cylindrical shaft;

FIG. 16 is a diagram showing a configuration of a drivetransmitting-side coupling according to the first embodiment;

FIG. 17 is a diagram showing an engagement between the drivetransmitting-side coupling and the metal plate cylindrical shaftaccording to the first embodiment;

FIG. 18 is a sectional view showing a positional relationship between adrive transmitting surface and the seam of the metal plate cylindricalshaft according to the first embodiment;

FIGS. 19A to 19C are diagrams showing a positional relationship betweena drive transmitting surface and a seam of a metal plate cylindricalshaft;

FIGS. 20A and 20B are diagrams showing a shape of a metal platecylindrical shaft according to a second embodiment;

FIG. 21 is a sectional view showing a configuration of a driveinput-side coupling according to the second embodiment;

FIG. 22 is a sectional view showing a positional relationship between adrive receiving surface and a seam of the metal plate cylindrical shaftaccording to the second embodiment;

FIGS. 23A to 23C are diagrams showing a positional relationship betweena drive receiving surface and a seam of a metal plate cylindrical shaft;

FIG. 24 is a diagram showing a configuration of a drivetransmitting-side coupling according to the second embodiment;

FIG. 25 is a sectional view showing a positional relationship between adrive transmitting surface and the seam of the metal plate cylindricalshaft according to the second embodiment; and

FIGS. 26A to 26C are sectional views showing a positional relationshipbetween a drive transmitting surface and a seam of a metal platecylindrical shaft.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a description will be given, with reference to thedrawings, of embodiments (examples) of the present invention. However,the sizes, materials, shapes, their relative arrangements, or the likeof constituents described in the embodiments may be appropriatelychanged according to the configurations, various conditions, or the likeof apparatuses to which the invention is applied. Therefore, the sizes,materials, shapes, their relative arrangements, or the like of theconstituents described in the embodiments do not intend to limit thescope of the invention to the following embodiments.

First Embodiment

As an image forming apparatus according to a first embodiment of thepresent invention, a full-color electrophotographic image formingapparatus image forming apparatus with four process cartridgesattachable thereto and detachable therefrom will now be exemplified.However, the number of process cartridges to be mounted to theelectrophotographic image forming apparatus (hereinafter, referred to animage forming apparatus) is not limited thereto and is to beappropriately set as necessary. For example, in the case of an imageforming apparatus that forms black and white images, the number ofprocess cartridges mounted to the image forming apparatus is one. Inaddition, while a printer will be exemplified as a mode of the imageforming apparatus in the embodiment described below, image formingapparatuses are not limited thereto. For example, the present inventioncan also be applied to other image forming apparatuses including as acopier and a facsimile apparatus as well as a multifunction machine thatcombines these functions.

FIG. 1 is an external perspective view of an image forming apparatusaccording to an embodiment of the present invention, and FIG. 2 is asectional schematic view of the image forming apparatus according to theembodiment of the present invention. This image forming apparatus 1 is afour-color full-color laser printer using an electrophotographic processwhich forms a color image on a sheet S. The image forming apparatus 1adopts a process cartridge system in which a process cartridge P(hereinafter, referred to as a cartridge) is detachably mounted to anapparatus main body 2 and a color image is formed on a sheet S.

With respect to the image forming apparatus 1, it is assumed that a sideon which an apparatus open/close door 3 and a cassette cover 10 (a coverof a paper feeding cassette that houses the sheet S as a recordingmaterial) is the front (a front surface) and a surface opposite to thefront is the rear (a back surface). In addition, a right side of theimage forming apparatus 1 as viewed from the front will be referred toas a driving side and a left side will be referred to as a non-drivingside.

In the apparatus main body 2, four cartridges P (PY, PM, PC, and PK)including a first cartridge PY, a second cartridge PM, a third cartridgePC, and a fourth cartridge PK are arranged in a horizontal direction.Each of the first to fourth cartridges P (PY, PM, PC, and PK) has asimilar electrophotographic process mechanism but has a developer(hereinafter, referred to as toner) of a different color. A rotationaldriving force is transmitted to the first to fourth cartridges P (PY,PM, PC, and PK) from a cartridge drive transmitting portion (not shown)of the apparatus main body 2.

In addition, bias voltage (a charging bias, a developing bias, and thelike) is supplied (not shown) to each of the first to fourth cartridgesP (PY, PM, PC, and PK) from the apparatus main body 2.

The first cartridge PY houses yellow (Y) toner and forms a yellow tonerimage on a surface of a photosensitive drum 30.

The second cartridge PM houses magenta (M) toner and forms a magentatoner image on the surface of the photosensitive drum 30.

The third cartridge PC houses cyan (C) toner and forms a cyan tonerimage on the surface of the photosensitive drum 30.

The fourth cartridge PK houses black (K) toner and forms a black tonerimage on the surface of the photosensitive drum 30.

A laser scanner unit LS as exposing means is provided above the first tofourth cartridges P (PY, PM, PC, and PK). The laser scanner unit LSoutputs laser light Z in correspondence with image information. Inaddition, the laser light Z passes through an exposure window portion ofthe cartridge P and scans and exposes the surface of the photosensitivedrum 30.

An intermediate transfer belt unit 11 as a transfer member is providedbelow the first to fourth cartridges P (PY, PM, PC, and PK). Theintermediate transfer belt unit 11 includes a driver roller 13, atension roller 17, and an assist roller 15, and a flexible transfer belt12 is stretched over the intermediate transfer belt unit 11. Thetransfer belt 12 is rotationally driven in a direction of an arrow C bythe driver roller 13. A rotational driving force is transmitted to thedriver roller 13 from a belt drive transmitting portion 50 (to bedescribed later) as a drive transmitting apparatus of the apparatus mainbody 2.

A lower surface of the photosensitive drum 30 of the first to fourthcartridges P (PY, PM, PC, and PK) is in contact with an upper surface ofthe transfer belt 12. The contact portion constitutes a first transferportion. A primary transfer roller 16 is provided so as to oppose thephotosensitive drum 30 on an inner side of the transfer belt 12. Asecondary transfer roller 14 abuts with the driver roller 13 via thetransfer belt 12. A contact portion between the transfer belt 12 and thesecondary transfer roller 14 constitutes a second transfer portion. Apaper feeding unit 18 is provided below the intermediate transfer beltunit 11. The paper feeding unit 18 includes a paper feeding cassette 19in which the sheet S is stacked and housed and a sheet paper feedingroller 20.

A fixing unit 21 and a discharging unit 22 are provided in upper left inthe apparatus main body 2 shown in FIG. 2. An upper surface of theapparatus main body 2 constitutes a discharge tray 23. A toner image isfixed to the sheet S by fixing means provided in the fixing unit 21, andthe sheet S is discharged to the discharge tray 23. The configurationdescribed above which is involved in the process of forming an image onthe sheet S (a recording material) corresponds to the image formingportion according to the present invention.

FIG. 3 is a perspective view showing an example of the intermediatetransfer belt unit 11. Moreover, in the present diagram, the transferbelt 12 is omitted. A roller-side coupling 60 that constitutes the beltdrive transmitting portion 50 is provided at one end of the driverroller 13. Hereinafter, details of the belt drive transmitting portion50 will be described.

FIG. 4 is a perspective view showing a configuration of the driverroller 13 and the belt drive transmitting portion 50. The belt drivetransmitting portion 50 according to the present embodiment isconstituted by the roller-side coupling 60 provided on the driver roller13, a bearing 70, and a drive input-side coupling 80 (to be describedlater) which is provided on a side of a driving source (not shown) andwhich is rotated by a driving force from the driving source. Moreover,in the present embodiment, a side on which the drive input-side coupling80 is arranged can be considered a transmitting portion that transmits adriving force, and a side on which the roller-side coupling 60 isarranged can be considered a receiving portion that receives the drivingforce.

The drive input-side coupling 80 is constituted by a drive transmittinggear 81, a drive transmitting plate 82, and a metal plate cylindricalshaft 83 that is a metallic drive transmitting member (a cylindricalshaft). Although details will be described later, a driving force fromthe driving source is transmitted in the order of the drive transmittinggear 81, the drive transmitting plate 82, and the metal platecylindrical shaft 83. Moreover, a drive transmitting mechanism 24 isprovided between the driving source and the drive transmitting gear 81.

Although details will be described later, the roller-side coupling 60 isconfigured to engage with the metal plate cylindrical shaft 83, and adriving force of the metal plate cylindrical shaft 83 is transmitted tothe roller-side coupling 60. The driver roller 13 includes a shaft 131(an example of the shaft member) formed in a columnar shape and acontact portion 132 which is cylindrically formed on an outercircumferential surface side of the shaft 131 and which is arranged soas to come into contact with an inner circumferential surface of thetransfer belt 12. In addition, the roller-side coupling 60 is arrangedon a side of one end of the shaft 131 and transmits a driving force froma side of the driving source to the shaft 131. Furthermore, in thepresent embodiment, the bearing 70 is provided in a different member(not shown) in the intermediate transfer belt unit 11, and theroller-side coupling 60 restricts movement of the shaft 131 in an axialdirection and towards a side of the contact portion 132.

Method of Creating Metal Plate Cylindrical Shaft

A manufacturing method of the metal plate cylindrical shaft 83 will nowbe described in detail with reference to FIGS. 5 to 8. The metal platecylindrical shaft 83 is a press-worked article produced by applying abending process to a metal plate and forming the metal plate into acylindrical shape.

FIG. 5 is a schematic diagram showing an apparatus configuration of amanufacturing apparatus of the metal plate cylindrical shaft 83. Themanufacturing apparatus of the metal plate cylindrical shaft 83 includesa transporting mechanism 150 that transports a metal plate 40, apunching stage 100 for punching the metal plate 40, bending stages 110,120, and 130 for performing a bending process, and a cutting stage 140for performing cutting in which parts are separated. The metal plate 40having a plate thickness of around 0.4 to 1.2 mm and wound in a coil isunwound by the transporting mechanism 150 and sent to the punching stage100. The punching stage 100 includes a male mold and a female mold forpunching. In the punching stage 100, by pressing the metal plate 40 withthe male mold and the female mold, unnecessary portions are cut awayfrom the metal plate 40 and removed and the metal plate 40 is formedinto a prescribed pre-bending shape.

FIG. 6 is a schematic diagram showing a shape of the metal plate 40after passing the punching stage 100. A cut shape 49 that is an I-shapedhole or a sideways H-shaped hole is cut out at a plurality of locationsat equal intervals from the metal plate 40. Although a notched portionto become a recessed groove for performing delivery of a driving forceand a hole to become a through hole in a final form of the metal platecylindrical shaft 83 are actually formed in the cut shape 49, suchdetails are omitted from the present diagram which represents aschematic view. In addition, due to the punching, the metal plate 40 isprocessed into a shape in which a plurality of flat plate portions 42 tobecome the metal plate cylindrical shaft 83 are connected to a frameportion via connecting portions 41. Edge portions 43 and 44 being bothends of the flat plate portion 42 in a transport direction (an Xdirection) of the metal plate 40 are portions which, when the flat plateportion 42 is formed into a cylindrical portion in a subsequent bendingprocess, become seam portions of the cylindrical portion. In addition,the connecting portion 41 is cut when the flat plate portion 42 is bentinto the cylindrical portion and separated from the frame portion. Asthe metal plate 40 is subjected to consecutive punching by the punchingstage 100, the shape described above is formed in plurality at equalintervals in the transport direction.

Bending will be described with reference to FIGS. 7A to 7D. FIGS. 7A to7D are schematic diagrams illustrating the bending process. The bendingstages 110 to 130 shown in FIG. 5 are provided side by side in thetransport direction (the X direction) of the metal plate 40.

FIG. 7A is a sectional view of one of the flat plate portions 42 of thepunched metal plate 40 as seen from a Y direction. Three bendingprocesses are performed in stages with respect to the flat plate portion42 by the bending stages 110 to 130.

FIG. 7B is a schematic diagram showing a first bending process. Thefirst bending process is performed at the bending stage 110. The bendingstage 110 includes a female mold 111 and a male mold 112. By beingsandwiched between the female mold 111 and the male mold 112, both sideportions of the flat plate portion 42 are bent relative to a centralportion so that end surfaces of the edge portions 43 and 44 facedownward.

FIG. 7C is a schematic diagram showing a second bending process. Thesecond bending process is performed at the bending stage 120. Thebending stage 120 includes a female mold 121 and a male mold 122. Abending process is performed in which the central portion of the flatplate portion 42 bent in the first process is inflected by the femalemold 121 and the male mold 122.

FIG. 7D is a schematic diagram showing a third bending process. Thethird bending process is performed at the bending stage 130. The bendingstage 130 includes a female mold 133 and a male mold 134. The flat plateportion 42 bent in the second process is now bent so as to acquire anoverall approximately cylindrical shape and worked so that the edgeportion 43 and the edge portion 44 are joined by the female mold 133 andthe male mold 134. Due to a seam portion 46 formed by bringing the edgeportions 43 and 44 in proximity with each other, the bent flat plateportion 42 acquires an approximately cylindrically connected shape.

Modes of the seam portion 46 include not only a mode in which the edgeportions 43 and 44 abut with each other but also a mode in which theedge portions 43 and 44 oppose each other in a circumferential directionacross a gap or, in other words, a mode in which the seam portion 46does not completely join the cylindrical portion. After the bendingprocess described above is completed, the metal plate 40 is in a statewhere a plurality of the metal plate cylindrical shafts 83 are connectedto the frame portion by the connecting portions 41. In addition, afterthe metal plate cylindrical shaft 83 is formed into a cylindrical shape,the connecting portion 41 is severed at the cutting stage 140 and themetal plate cylindrical shaft 83 is formed into a final form.

FIGS. 8A and 8B show the metal plate cylindrical shaft 83 in its finalform according to the first embodiment. The metal plate cylindricalshaft 83 fabricated by the process described above has, as a seam 830, apair of circumferential ends which oppose or abut with each other in thecircumferential direction from one end to another end in the axialdirection. While the seam 830 has a linear shape in the presentembodiment, as shown in FIGS. 9A and 9B, a configuration may be adoptedin which a recessed shape that is recessed in the circumferentialdirection is provided at one end and a protruded shape that protrudes inthe circumferential direction is provided at the other end opposing theone end and the recessed shape and the protruded shape fit each other.Accordingly, a deviation in the axial direction of both end surfaces ofthe seam 830 can be suppressed.

Moreover, an angle between an end surface and a side surface in aprotruding direction of the protruded shape and an angle between an endsurface and a side surface in a recessing direction of the recessedshape provided on the end surfaces of the seam 830 are set at anapproximately right angle in consideration of easiness of bending.Alternatively, the angles may be formed as obtuse angles (smaller than180 degrees). In other words, the protruded portion may be given atapered shape in which the closer to a tip, the narrower a width in theaxial direction, and the recessed portion may be given a flared shape inwhich the closer to an opening side, the wider a width in the axialdirection (the closer to a bottom side, the narrower the width in theaxial direction). Alternatively, a combination of the recessed shape andthe protruded shape can be provided in plurality or the protruded shapeand the recessed shape can be alternately arranged on one end.

In addition, as a notched portion that is recessed in the axialdirection on an approximately annular end surface at an end in the axialdirection, the metal plate cylindrical shaft 83 includes a recessedgroove 831 and a recessed groove 832. Although details will be givenlater, the recessed groove 831 and the recessed groove 832 are torespectively constitute a driving force delivery portion with theroller-side coupling 60 and the drive transmitting plate 82.

Drive Input-Side Coupling

A configuration of the drive input-side coupling 80 will be describedwith reference to FIGS. 10 to 13. FIG. 10 is a diagram showing aconfiguration of the belt drive transmitting portion 50 as viewed fromthe front of the main body. FIG. 11 is a sectional view of the driveinput-side coupling 80 passing through a center of the metal platecylindrical shaft 83 as viewed from a same direction as FIG. 10. FIG. 12shows a cross section taken along line D-D in FIG. 10. FIG. 13 shows across section taken along line B-B in FIG. 10.

As described earlier, the drive input-side coupling 80 is provided on aside of the driving source (not shown) in the belt drive transmittingportion 50, and the drive transmitting gear 81 receives a driving force(a rotating force) from the drive transmitting mechanism 24 andtransmits the driving force to the metal plate cylindrical shaft 83 viathe drive transmitting plate 82.

As shown in FIG. 11, a shaft-like central projecting portion 812 isprovided at a center of the drive transmitting gear 81 and a groove 813is provided at a base of the central projecting portion 812. In thiscase, as shown in FIGS. 11 and 13, since the central projecting portion812 is to be inserted to an inner circumferential portion of the metalplate cylindrical shaft 83, the metal plate cylindrical shaft 83 isconfigured such that an inner circumferential diameter thereof is largerthan an outer circumferential diameter of the central projecting portion812. In addition, an inner circumferential surface 813 a that is aninner surface of the groove 813 on an outer side in the radial directionis configured such that an outer circumferential surface of the metalplate cylindrical shaft 83 comes into fitting contact therewith.

Furthermore, the metal plate cylindrical shaft 83 is provided with anapproximately circular through-hole 833 and, due to a stopper 84 beingattached so as to penetrate the metal plate cylindrical shaft 83 and theprojecting portion 812, positions of the drive transmitting gear 81 andthe metal plate cylindrical shaft 83 in the axial direction arerestricted. FIG. 13 shows a state where the stopper 84 is inserted intothe through-hole 833 and penetrates the central projecting portion 812of the drive transmitting gear 81 and the metal plate cylindrical shaft83. The stopper 84 according to the present embodiment is formed of aresin material and is constituted by, as shown in FIG. 12, a shaftportion 841 penetrating the through-hole 833 of the metal platecylindrical shaft 83 and an arm portion 842 formed so as to conform toan outer shape of the metal plate cylindrical shaft 83. The arm portion842 is configured to be attachable to the metal plate cylindrical shaft83 by coming into contact with the outer circumference of the metalplate cylindrical shaft 83 and deforming so as to open.

In addition, by attaching the metal plate cylindrical shaft 83 so thatthe outer circumferential surface of the metal plate cylindrical shaft83 comes into fitting contact with the inner circumferential surface 813a of the groove 813, a central axis of the drive transmitting gear 81and a central axis of the metal plate cylindrical shaft 83 are made tocoincide with each other. Accordingly, unevenness in rotation of themetal plate cylindrical shaft 83 is reduced and drive transmission withhigh accuracy can be realized. Moreover, while the outer circumferentialsurface of the metal plate cylindrical shaft 83 and the innercircumferential surface 813 a of the groove 813 of which dimensionalaccuracy is readily attainable when machining the metal platecylindrical shaft are brought into fitting contact with each other inthe present embodiment, this configuration is not restrictive. Forexample, the central axis of the drive transmitting gear 81 and thecentral axis of the metal plate cylindrical shaft 83 can be made tocoincide with each other by bringing an inner circumferential surface ofthe metal plate cylindrical shaft 83 and an outer circumferentialsurface of the central projecting portion 812 into fitting contact witheach other.

As shown in FIG. 13, one or a plurality of projecting portions 811 areprovided on a same circumference at a predetermined distance from acenter of a gear pitch circle in a side surface portion of the drivetransmitting gear 81. A drive transmitting surface 811 a is provided ona forward side in a rotation direction C of the drive transmitting gear81 on the projecting portion 811. Meanwhile, the drive transmittingplate 82 is a plate with a shape approximately resembling a shuriken (aninja star) having one or a plurality of notches 821 with respect to anoutermost circumferential surface of a circle. The notch 821 is providedon a forward side in a rotation direction in the notch with adrive-transmitted surface 821 a configured to come into contact in acircumferential direction with the drive transmitting surface 811 a ofthe projecting portion 811 provided on the drive transmitting gear 81. Acontact surface of the drive transmitting surface 811 a and thedrive-transmitted surface 821 a is positioned on a line connecting anarbitrary point on a circumference of the gear and a center of the gear.Accordingly, an orientation of a force applied at the contact surfacecan be made to coincide with the rotation direction and drivetransmission loss can be suppressed.

An approximately circular hole 823 is provided at a central portion ofthe drive transmitting plate 82, and one or a plurality of protrudedportions 822 are provided so as to protrude toward the center (inward ina radial direction) from an inner circumferential surface of the hole823. Moreover, a position of the drive transmitting plate 82 in the Ydirection is restricted in one direction by colliding with a sidesurface of the drive transmitting gear 81 and restricted in an oppositedirection by a restricting member (not shown) provided so as to engagewith the metal plate cylindrical shaft 83. While the recessed groove 832is provided at an end of the metal plate cylindrical shaft 83 on theside of the drive transmitting gear 81, as shown in FIG. 13, a width ofthe recessed groove 832 in a circumferential direction is configured tobe larger than a width in a circumferential direction of the protrudedportion 822 in the drive transmitting plate 82. In addition, an outercircumferential diameter of the metal plate cylindrical shaft 83 isconfigured to be smaller than a diameter of the hole 823 provided at thecentral portion of the drive transmitting plate 82.

Details of drive transmission from the drive transmitting gear 81 to themetal plate cylindrical shaft 83 will now be described. First, drivetransmission from the drive transmitting gear 81 to the drivetransmitting plate 82 is performed between the drive transmittingsurface 811 a of the drive transmitting gear 81 and thedrive-transmitted surface 821 a of the drive transmitting plate 82 whichabut with each other in the circumferential direction. In this case,since the contact surface of the drive transmitting surface 811 a andthe drive-transmitted surface 821 a is provided at a predetermineddistance from the center of the drive transmitting gear 81, a forceapplied to the contact surface in accordance with a distance from thegear center can be reduced with respect to on-axis torque. In addition,by providing the drive transmitting surface 811 a and thedrive-transmitted surface 821 a in plurality, an applied load per onelocation of the drive transmitting surface 811 a on the gear can bedistributed in accordance with the number of the provided surfaces.

As shown in FIG. 14, drive transmission from the drive transmittingplate 82 as the first member to the metal plate cylindrical shaft 83 isperformed at a contact portion between the protruded portion 822 of thedrive transmitting plate 82 and the recessed groove 832 provided at oneend of the metal plate cylindrical shaft 83. The contact portion of therecessed groove 832 with the protruded portion 822 corresponds to theforce receiving portion according to the present invention.

In the contact portion between the protruded portion 822 of the drivetransmitting plate 82 and the recessed groove 832 of the metal platecylindrical shaft 83, let 832A denote a contact point nearest to theseam 830 of the metal plate cylindrical shaft 83 in an oppositedirection to the rotation direction C of the metal plate cylindricalshaft 83. The contact portion of the recessed groove 832 with theprotruded portion 822 corresponding to the contact point 832Acorresponds to the first force receiving portion according to thepresent invention. In the recessed groove 832, a portion correspondingto the contact point 832A is a portion that receives force in thecircumferential direction from the protruded portion 822 of the drivetransmitting plate 82 and is a contact portion nearest to the seam 830in an opposite direction to a direction in which the force is received.In addition, let 832B denote a contact point nearest to the seam 830 inthe rotation direction of the metal plate cylindrical shaft 83. Thecontact portion of the recessed groove 832 with the protruded portion322 corresponding to the contact point 832B corresponds to the secondforce receiving portion according to the present invention. In therecessed groove 832, a portion corresponding to the contact point 832Bis a contact portion nearest to the seam 830 in the direction in whichthe force is received.

In the present embodiment, two recessed grooves 832 are provided asforce-receiving notched portions. One recessed groove 832 (the firstnotched portion) is provided at a position nearest to the seam 830 inthe opposite direction to the rotation direction C (the direction inwhich a force is received from the protruded portion 822) of the metalplate cylindrical shaft 83. A contact portion in the one recessed groove832 (the first notched portion) with the protruded portion 822corresponds to the contact point 832A. In addition, the other recessedgroove 832 (the second notched portion) is provided at a positionnearest to the seam 830 in the rotation direction C (the direction inwhich a force is received from the protruded portion 822) of the metalplate cylindrical shaft 83. A contact portion in the other recessedgroove 832 (the second notched portion) with the protruded portion 822corresponds to the contact point 832B. The other recessed groove 832(the second notched portion) is at a position farther from the seam 830in the circumferential direction than the one recessed groove 832 (thefirst notched portion).

FIG. 14 is a partial sectional view through the contact points 832A and832B of the metal plate cylindrical shaft 83 and the drive transmittingplate 82 in a same direction as FIG. 13. FIG. 14 shows a positionalrelationship between the contact points 832A and 832B that are drivetransmission points between the metal plate cylindrical shaft 83 and thedrive transmitting plate 82 and the seam 830 of the metal platecylindrical shaft 83. In FIG. 14, a point O denotes a center (arotational center) of the metal plate cylindrical shaft, a point Pdenotes an intersection of the seam 830 and the inner circumferentialsurface of the metal plate cylindrical shaft 83, and points A₂ and B₂respectively denote the contact points 832A and 832B on the sectionalview. Moreover, the metal plate cylindrical shaft 83 according to thepresent embodiment is worked into a cylindrical shape by bending afterperforming a punching process on a metal plate. Therefore, the endsurfaces of the recessed grooves 831 and 832, the end surface of thethrough-hole 833, both ends of the metal plate at the seam 830, and thelike tend to become inclined so as to open from an inner circumferencetoward an outer circumference of the metal plate cylindrical shaft 83 ona plane perpendicular to the axis of the metal plate cylindrical shaft83. Accordingly, the contact point between the metal plate cylindricalshaft 83 and the drive transmitting plate 82 is on a circumference ofthe inner circumferential surface of the metal plate cylindrical shaft83.

As shown in FIG. 14, let ∠A₂OP denote a central angle (the first centralangle) of an imaginary arc (the first imaginary arc) which has therotational center O of the metal plate cylindrical shaft 83 as itscenter and which connects the contact point 832A of the metal platecylindrical shaft 83 and the seam 830 in the rotation direction C of themetal plate cylindrical shaft 83. In addition, let ∠B₂OP denote acentral angle (the second central angle) of an imaginary arc (the secondimaginary arc) which has the rotational center O of the metal platecylindrical shaft 83 as its center and which connects the contact point832B of the metal plate cylindrical shaft 83 and the seam 830 in anopposite direction to the rotation direction C of the metal platecylindrical shaft 83. In the present embodiment, the respective recessedgrooves 832 and the seam 830 are provided at different positions in thecircumferential direction when the metal plate cylindrical shaft 83 isviewed in the axial direction so that the first central angle of thefirst imaginary arc becomes smaller than the second central angle of thesecond imaginary arc. In other words, in FIG. 14, the respective drivereceiving portions (the force receiving portions) or, in other words,the recessed grooves 832 to become contact portions with the drivetransmitting plate 82 are provided so that ∠A₂OP<∠B₂OP is satisfied.Hereinafter, the reason for setting the positional relationship betweenthe seam 830 of the metal plate cylindrical shaft 83 and the drivereceiving portion points 832A and 832B as described above will beexplained.

FIGS. 15A to 15C are schematic diagrams showing arrangements of therecessed groove 832 and the seam 830 in the form of a comparison betweenthe arrangement according to the present embodiment and arrangementsaccording to comparative examples. FIG. 15A is a schematic diagram (adiagram as viewed in the axial direction) of the metal plate cylindricalshaft 83 in a case (the present embodiment) in which the drive receivingportions are arranged so as to satisfy ∠A₂OP<∠B₂OP. FIG. 15B is aschematic diagram of the metal plate cylindrical shaft 83 in a case (afirst comparative example) in which the drive receiving portions arearranged so as to satisfy ∠A₂OP>∠B₂OP. FIG. 15C is a schematic diagramof the metal plate cylindrical shaft 83 in a case (a second comparativeexample) in which the recessed grooves 832 are provided on the seam 830(provided at overlapping positions in the circumferential direction asviewed in the axial direction).

When a driving force is transmitted to the metal plate cylindrical shaft83 and forces are applied at the contact points A₂ and B₂, in thearrangement shown in FIG. 15C, the forces are applied in directions thatcause the seam 830 to open. In the arrangement shown in FIG. 15B, sincethe forces act in directions that cause the seam 830 to open and indirections that cause the seam 830 to deviate in a radial direction,torsion of the shaft may possibly increase. Conversely, in thearrangement shown in FIG. 15A, since the forces are applied indirections that cause the seam 830 to close, the seam is prevented fromopening. In addition, in the arrangement shown in FIG. 15A, although theforces are also applied in directions causing a deviation of the metalplate cylindrical shaft 83 in the radial direction in a similar mannerto FIG. 15B, due to ends of a metal plate coming into contact with eachother at the seam 830, the forces applied in directions causing the seam830 to close become forces that push the ends of the metal plate of theseam 830 against each other. Accordingly, a friction force between theends of the metal plate of the seam 830 increases and a deviation of themetal plate cylindrical shaft 83 in the radial direction can besuppressed.

Therefore, the present embodiment adopts the configuration shown in FIG.15A in which the seam 830 is less likely to open and a deviation of themetal plate cylindrical shaft 83 in the radial direction is less likelyto occur. In addition, by arranging the recessed grooves 832 in thismanner, the seam 830 of the metal plate cylindrical shaft 83 isprevented from opening or deviating and a torsional strength of themetal plate cylindrical shaft 83 is prevented from declining. Moreover,while a configuration in which ∠A₂OP is an acute angle and ∠B₂OP is anobtuse angle is adopted in the present embodiment, this configuration isnot restrictive. For example, a configuration in which ∠B₂OP is anapproximately right angle can be appropriately adopted as long as theeffect described above is produced.

In addition, a deviation of the ends of a metal plate at the seam 830 inthe axial direction of the metal plate cylindrical shaft 83 can besuppressed by providing the seam 830 with a recessed shape and aprotruded shape and causing the recessed shape and the protruded shapeto fit with each other as shown in FIGS. 9A and 9B.

Drive Transmitting-Side Coupling

The roller-side coupling 60 will now be described with reference to FIG.16. FIG. 16 is a schematic perspective view for describing theroller-side coupling 60. The roller-side coupling 60 according to thepresent embodiment includes a pin 61 to be inserted to a through-hole131 b formed on the shaft 131 and a resin cover member 62 to be attachedto the shaft 131. In addition, although not shown in FIG. 16, theroller-side coupling 60 also includes the bearing 70 (refer to FIG. 4).The cover member 62 is formed in an approximately double annular shapeand includes an outer ring portion 621 (the second annular portion), aninner ring portion 622 (the first annular portion), and a base portion623 (the coupling portion) that connects the outer ring portion and theinner ring portion with each other. Recessed grooves 622 a as engagingportions capable of engaging with the pin 61 in a rotation direction areformed in the inner ring portion 622 at two positions opposing a centerof the inner ring.

The pin 61 as an example of a delivery member and an inserted member isformed in a columnar shape and is inserted to the through-hole 131 bformed on the shaft 131 in a non-press-fitted state and arranged in astate where the both ends of the pin 61 protrude from the outercircumferential surface of the shaft 131. Both protruding ends of thepin 61 are restricted by the resin cover member 62, and the resin covermember 62 also restricts movement of the pin 61 in a thrust direction inthe through-hole.

FIG. 17 shows how the roller-side coupling 60 engages with the metalplate cylindrical shaft 83. The pin 61 is configured so as to engagewith the metal plate cylindrical shaft 83. The recessed grooves 831 attwo locations as notched portions provided on the metal platecylindrical shaft 83 are arranged so as to hold the pin 61, and drive istransmitted from the metal plate cylindrical shaft 83 to the pin 61 asthe second member. Therefore, an outer diameter of the pin 61 isconfigured smaller than a width of the recessed grooves 831. Inaddition, as drive is transmitted and the pin 61 inserted to thethrough-hole 131 b of the shaft 131 rotates, the shaft 131 or, in otherwords, the driver roller 13 rotates.

As shown in FIG. 18, drive transmission from the metal plate cylindricalshaft 83 to the pin 61 as the second member is performed at a contactportion between the recessed grooves 831 of the metal plate cylindricalshaft 83 and the pin 61. The contact portion of the recessed grooves 831with the pin 61 corresponds to the force receiving portion as a portionthat receives a reaction force from the second member when driving thesecond member and also corresponds to the force applying portion thatcauses the driving force received from the first member to act on thesecond member according to the present invention.

In the contact portion between the recessed grooves 832 of the metalplate cylindrical shaft 83, let 831A denote a contact point nearest tothe seam 830 of the metal plate cylindrical shaft 83 in an oppositedirection (a direction in which a reaction force is received from thepin 61) to the rotation direction C of the metal plate cylindrical shaft83. The contact portion of the recessed groove 831 with the pin 61 whichcorresponds to the contact point 831A corresponds to the second forcereceiving portion as well as the second force applying portion accordingto the present invention. In the recessed groove 831, a portioncorresponding to the contact point 831A is a portion that receives areaction force in the circumferential direction from the pin 61 and is acontact portion nearest to the seam 830 in a direction in which thereaction force is received. In addition, let 831B denote a contact pointnearest to the seam 830 in the rotation direction C (an oppositedirection to the direction in which the reaction force is received fromthe pin 61) of the metal plate cylindrical shaft 83. The contact portionof the recessed groove 831 with the pin 61 which corresponds to thecontact point 831B corresponds to the first force receiving portion aswell as the first force applying portion according to the presentinvention. In the recessed groove 831, a portion corresponding to thecontact point 831B is a portion that receives a reaction force from thepin 61 in the circumferential direction and is a contact portion nearestto the seam 830 in the opposite direction to the direction in which thereaction force is received.

In the present embodiment, two recessed grooves 831 are provided asforce-applying notched portions. One recessed groove 831 (the firstnotched portion) is provided at a position nearest to the seam 830 inthe rotation direction C (a direction in which a force is applied to thepin 61, and an opposite direction to the direction in which a reactionforce is received from the pin 61) of the metal plate cylindrical shaft83. A contact portion in the one recessed groove 831 (the first notchedportion) with the pin 61 corresponds to the contact point 831B. Inaddition, the other recessed groove 831 (the second notched portion) isprovided at a position nearest to the seam 830 in an opposite direction(a direction in which a reaction force is received from the pin 61) tothe rotation direction C (a direction in which a force is applied to thepin 61) of the metal plate cylindrical shaft 83. A contact portion inthe other recessed groove 831 (the second notched portion) with the pin61 corresponds to the contact point 831A. The other recessed groove 831(the second notched portion) is at a position farther from the seam 830in the circumferential direction than the one recessed groove 831 (thefirst notched portion).

FIG. 18 is a schematic sectional view showing a positional relationshipamong the shaft 131, the resin cover member 62, and the metal platecylindrical shaft 83 as well as a positional relationship between thecontact points 831A and 831B that are drive transmission points betweenthe metal plate cylindrical shaft 83 and the pin 61 and the seam 830.FIG. 18 shows a cross section passing through the contact points 831Aand 831B of the metal plate cylindrical shaft 83 when viewed from a sideof an end where the recessed groove 831 is provided in the axialdirection of the metal plate cylindrical shaft 83. In FIG. 18, C denotesthe rotation direction of the metal plate cylindrical shaft, a point Odenotes a center (a rotational center) of the metal plate cylindricalshaft on the sectional view in FIG. 18, a point P denotes anintersection of a center line of the seam 830 and a circumference of theinner circumferential surface of the metal plate cylindrical shaft 83,and points A₁ and B₁ respectively denote the contact points 831A and831B. In the present embodiment, as shown in FIG. 18, an innercircumferential surface of the inner ring portion 622 of the resin covermember 62 is in slidable contact with the shaft 131, and the outer ringportion 621 is provided with a plurality of ribs 624 a so as to comeinto fitting contact with the metal plate cylindrical shaft 83.Accordingly, a central axis of the shaft 131 and the central axis of themetal plate cylindrical shaft are made to coincide with each other.Moreover, an outer circumferential surface of the inner ring portion 622is configured to be smaller than a diameter of the outer circumferentialsurface of the metal plate cylindrical shaft. In addition, as describedearlier, in the metal plate cylindrical shaft 83, the end surfaces ofthe recessed grooves 831 and 832, both ends of the metal plate at theseam 830, and the like tend to become inclined so as to open from theinner circumference toward the outer circumference of the metal platecylindrical shaft 83 on a plane perpendicular to the axis of the metalplate cylindrical shaft 83. Accordingly, the contact point between themetal plate cylindrical shaft 83 and the pin 61 is on a circumference ofthe inner circumferential surface of the metal plate cylindrical shaft83.

As shown in FIG. 18, let ∠A₁OP denote a central angle (the secondcentral angle) of an imaginary arc (the second imaginary arc) which hasthe rotational center O of the metal plate cylindrical shaft 83 as itscenter and which connects the contact point 831A of the metal platecylindrical shaft 83 and the seam 830 in the rotation direction C of themetal plate cylindrical shaft 83. In addition, let ∠B₁OP denote acentral angle (the first central angle) of an imaginary arc (the firstimaginary arc) which has the rotational center O of the metal platecylindrical shaft 83 as its center and which connects the contact point831B of the metal plate cylindrical shaft 83 and the seam 830 in theopposite direction to the rotation direction C of the metal platecylindrical shaft 83. In the present embodiment, the respective recessedgrooves 831 and the seam 830 are provided at different positions in thecircumferential direction when the metal plate cylindrical shaft 83 isviewed in the axial direction so that the first central angle of thefirst imaginary arc becomes smaller than the second central angle of thesecond imaginary arc. In other words, in FIG. 18, the respective drivetransmitting portions (the force applying portions that are also theforce receiving portions) or, in other words, the recessed grooves 831to become contact portions with the pin 61 are arranged so that∠A₁OP>∠B₁OP is satisfied.

FIGS. 19A to 19C are schematic diagrams showing arrangements of therecessed grooves 831 and the seam 830 in the form of a comparisonbetween the arrangement according to the present embodiment andarrangements according to comparative examples. FIG. 19A is a schematicdiagram (a diagram as viewed in the axial direction) of the metal platecylindrical shaft 83 in a case (the present embodiment) in which thedrive transmitting portions are arranged so as to satisfy ∠A₁OP>∠B₁OP.FIG. 19B is a schematic diagram of the metal plate cylindrical shaft 83in a case (a third comparative example) in which the drive transmittingportions are arranged so as to satisfy ∠A₁OP<∠B₁OP. FIG. 19C is aschematic diagram of the metal plate cylindrical shaft 83 in a case (afourth comparative example) in which the recessed grooves 831 areprovided on the seam 830 (provided at overlapping positions in thecircumferential direction).

When the metal plate cylindrical shaft 83 transmits a driving force tothe pin 61, at drive transmitting portion points A₁and B₁, the metalplate cylindrical shaft 83 receives a reaction force to the forceapplied to the pin 61 by the metal plate cylindrical shaft 83. When adriving force is transmitted by the metal plate cylindrical shaft 83 andforces are applied at the contact points A₁and B₁, in the arrangementshown in FIG. 19C, the forces are applied in directions that cause theseam 830 to open. In the arrangement shown in FIG. 19B, since the forcesact in directions that cause the seam 830 to open and in directions thatcause the seam 830 to deviate in a radial direction, torsion of theshaft may possibly increase. Conversely, in the arrangement shown inFIG. 19A, since the forces are applied in directions that cause the seam830 to close, the seam is prevented from opening. In addition, in thearrangement shown in FIG. 19A, although the forces are also applied indirections causing a deviation of the metal plate cylindrical shaft 83in the radial direction in a similar manner to FIG. 19B, due to ends ofa metal plate coming into contact with each other at the seam 830, theforces applied in directions causing the seam 830 to close become forcesthat push the ends of the metal plate of the seam 830 against eachother. Accordingly, due to an increase in a friction force between theends of the metal plate of the seam 830, a deviation of the metal platecylindrical shaft 83 in the radial direction can be suppressed.

Therefore, the present embodiment adopts the configuration shown in FIG.19A in which the seam 830 is less likely to open and a deviation of themetal plate cylindrical shaft 83 in the radial direction is less likelyto occur. In addition, by arranging the recessed grooves 831 in thismanner, the seam 830 of the metal plate cylindrical shaft 83 isprevented from opening or deviating and a torsional strength of themetal plate cylindrical shaft 83 is prevented from declining. Moreover,while a configuration in which ∠B₁OP is an acute angle and ∠A₁OP is anobtuse angle is adopted in the present embodiment, this configuration isnot restrictive. For example, a configuration in which ∠A₁OP is anapproximately right angle can be appropriately adopted as long as theeffect described above is produced.

As described above, in the metal plate cylindrical shaft 83 that is ametallic drive transmitting member, by configuring a positionalrelationship among the seam 830 of ends of a metal plate, a drivereceiving portion on a drive input side, and a drive transmittingportion on a drive transmitting side as in the present embodiment,torsional strength of the metal plate cylindrical shaft 83 can beprevented from declining. Therefore, even with a hollow-structurecylindrical shaft created by forming a metal plate into a cylindricalshape, an inexpensive and readily workable drive transmitting mechanism(a drive transmitting apparatus) with high drive transmission accuracycan be provided without having to provide a shape requiring specialmachining considerations and without having to apply welding or adhesionto the seam 830.

Second Embodiment

A second embodiment of the present invention will now be described withreference to FIGS. 20A and 20B to FIGS. 26A to 26C. Moreover, the secondembodiment only differs from the first embodiment in a shape of a metalplate cylindrical shaft that is a metallic drive transmitting member, adrive transmitting-side coupling, and a shape of a part of a roller-sidecoupling, while other portions are similar to the first embodiment and adescription thereof will be omitted.

FIGS. 20A and 20B are diagrams showing a shape of a metal platecylindrical shaft 283. In the present embodiment, one each of recessedgrooves 2831 and 2832 for drive transmission is provided on the metalplate cylindrical shaft. Specifically, a configuration is adopted whichis provided with one each of the force-receiving notched portion thatengages with the first member and receives a driving force of the firstmember in a circumferential direction and the force-applying notchedportion that engages with the second member and causes the driving forcereceived from the first member to act on the second member in thecircumferential direction according to the present invention. Inaddition, in the present embodiment, the first force receiving portionand the second force receiving portion according to the presentinvention are constituted by a same force receiving portion in a singleforce-receiving notched portion. In a similar manner, in the presentembodiment, the first force applying portion and the second forceapplying portion according to the present invention are constituted by asame force applying portion in a single force-applying notched portion.

FIG. 21 is a diagram which shows a configuration of a drive input-sidecoupling 280 that constitutes a drive input side according to the secondembodiment and which corresponds to FIG. 13 according to the firstembodiment. As shown in FIG. 21, one each of the recessed groove 2832 ofthe metal plate cylindrical shaft 283 and a protruded portion 2822 of adrive transmitting plate 282 is provided. In addition, a driving forcetransmitted from a driving source (not shown) to the drive transmittingplate 282 is transmitted from the drive transmitting plate 282 to themetal plate cylindrical shaft 283 at a contact point 2832A between theprotruded portion 2822 protruding from an inner circumference of a hole2823 of the drive transmitting plate 282 and the recessed groove 2832.

FIG. 22 is a diagram which shows a positional relationship between thecontact point 2832A that is a drive transmission point of the metalplate cylindrical shaft 283 with the drive transmitting plate 282 and aseam 2830 and which represents a sectional view (that corresponds toFIG. 14 according to the first embodiment) passing through the contactpoint 2832A. In the sectional view shown in FIG. 22, a point O denotes acenter (a rotational center) of the metal plate cylindrical shaft 283, apoint P denotes an intersection of the seam 2830 and an innercircumferential surface of the metal plate cylindrical shaft 283, and apoint A denotes the contact point 2832A. In the present embodiment, asshown in FIG. 22, an arrangement is adopted so that a central angle ofan imaginary arc connecting the seam 2830 and the contact point 2832A inan opposite direction to the rotation direction C becomes smaller than acentral angle of an imaginary arc connecting the seam 2830 and thecontact point 2832A in the rotation direction C.

In this case, the imaginary arc connecting the seam 2830 and the contactpoint 2832A in the opposite direction (an opposite direction to adirection in which force is received) to the rotation direction Ccorresponds to the first imaginary arc according to the presentinvention. Specifically, a portion of the metal plate cylindrical shaft283 at the contact point 2832A when connecting the seam 2830 and thecontact point 2832A in the opposite direction to the rotation directionC corresponds to the drive transmitting portion (the first forcereceiving portion) nearest to the seam 2830 in the opposite direction.In addition, the imaginary arc connecting the seam 2830 and the contactpoint 2832A in the rotation direction C (the direction in which force isreceived) corresponds to the second imaginary arc according to thepresent invention. Specifically, a portion of the metal platecylindrical shaft 283 at the contact point 2832A when connecting theseam 2830 and the contact point 2832A in the rotation direction Ccorresponds to the drive transmitting portion (the second forcereceiving portion) nearest to the seam 2830 in the rotation direction C(the direction in which force is received).

In other words, since only one drive transmission point 2832A isprovided in the present embodiment, the drive receiving portion nearestto the seam 2830 in the opposite direction to the rotation direction Cand the drive receiving portion nearest to the seam 2830 in the rotationdirection C are the same drive transmission point. Therefore, when∠A_(ccw)OP denotes an angle from the point P to the point Ain theopposite direction to the rotation direction C and ∠A_(cw)OP denotes anangle from the point P to the point A in the rotation direction C, therecessed groove 2832 is arranged so that ∠A_(ccw)OP becomes smaller than∠A_(cw)OP.

FIGS. 23A to 23C are schematic diagrams showing arrangements of therecessed groove 2832 and the seam 2830 in the form of a comparisonbetween the arrangement according to the present embodiment andarrangements according to comparative examples. FIG. 23A is a diagram ina case (the present embodiment) in which the drive receiving portion isarranged with respect to the metal plate cylindrical shaft 283 asdescribed above so as to satisfy ∠A_(ccw)OP<∠A_(cw)OP. FIG. 23B is adiagram in a case (a fifth comparative example) which, conversely,satisfies ∠A_(ccw)OP>∠A_(cw)OP, and FIG. 23C is a diagram in a case (asixth comparative example) in which the recessed groove 2832 is providedon the seam 2830 (provided at overlapping positions in thecircumferential direction as viewed in the axial direction).

When a driving force is transmitted to the metal plate cylindrical shaft283 and a force is applied at the contact point A, with the arrangementshown in FIG. 23C, the force is applied in a direction that causes theseam 2830 to open. In the arrangement shown in FIG. 23B, since the forceact in a direction that causes the seam 2830 to open and in a directionthat causes the seam 2830 to deviate in a radial direction, torsion ofthe shaft may possibly increase. Conversely, in the arrangement shown inFIG. 23A, since a force is applied in a direction that causes the seam2830 to close, the seam is prevented from opening. In addition, in thearrangement shown in FIG. 23A, although a force is also applied in adirection causing a deviation of the metal plate cylindrical shaft 283in the radial direction in a similar manner to FIG. 23B, due to ends ofa metal plate coming into contact with each other at the seam 2830, theforce applied in a direction causing the seam 2830 to close becomes aforce that pushes the ends of the metal plate at the seam 2830 againsteach other. Accordingly, due to an increase in a friction force betweenthe ends of the metal plate of the seam 2830, a deviation of the metalplate cylindrical shaft 283 in the radial direction can be suppressed.

Therefore, the present embodiment adopts the configuration shown in FIG.23A in which the seam 2830 is less likely to open and a deviation of themetal plate cylindrical shaft 283 in the radial direction is less likelyto occur. In addition, a deviation of the ends of the metal plate at theseam 2830 in the axial direction of the metal plate cylindrical shaft283 can be suppressed by providing the seam 2830 with a recessed shapeand a protruded shape and causing the recessed shape and the protrudedshape to fit with each other as shown in FIGS. 9A and 9B.

FIG. 24 is a diagram which shows a configuration of a roller-sidecoupling 260 that constitutes a drive transmitting side and whichcorresponds to FIG. 16 according to the first embodiment. In the presentembodiment, a pin 261 is inserted in a non-press-fitted state to athrough-hole 2131 b provided on a shaft 2131, and only one end of thepin 261 protrudes from an outer circumferential surface of the shaft2131 and is held by the recessed groove 2831 provided on the metal platecylindrical shaft 283. A resin cover member 262 to be attached to theshaft 2131 is formed in an approximately double annular shape andincludes an outer ring portion 2621 (the second annular portion), aninner ring portion 2622 (the first annular portion), and a base portion2623 (the coupling portion) that connects the outer ring portion and theinner ring portion with each other. A recessed groove 2622 a as anengaging portion capable of engaging with the pin 261 in a rotationdirection is formed in the inner ring portion 2622.

FIG. 25 is a diagram which shows a positional relationship between acontact point 2831B that is a drive transmission point between the metalplate cylindrical shaft 283 and the pin 261 and a seam 2830 and whichrepresents a sectional view (that corresponds to FIG. 18 according tothe first embodiment) passing through the contact point 2831B of themetal plate cylindrical shaft 283. In a similar manner to the firstembodiment, in FIG. 25, C denotes a rotation direction of the metalplate cylindrical shaft, a point O denotes a center of the metal platecylindrical shaft, a point P denotes an intersection of the seam 2830and an inner circumferential surface of the metal plate cylindricalshaft, and a point B denotes the contact point 2831B. In the presentembodiment, as shown in FIG. 25, an arrangement is adopted so that acentral angle of an imaginary arc connecting the seam 2830 and thecontact point 2831B in an opposite direction to the rotation direction Cbecomes larger than a central angle of an imaginary arc connecting theseam 2830 and the contact point 2831B in the rotation direction C.

In this case, the imaginary arc connecting the seam 2830 and the contactpoint 2831B in the opposite direction (a direction in which force isreceived) to the rotation direction C corresponds to the secondimaginary arc according to the present invention. Specifically, aportion of the metal plate cylindrical shaft 283 at the contact point2831B when connecting the seam 2830 and the contact point 2831B in theopposite direction to the rotation direction C corresponds to the drivetransmitting portion (the second force receiving portion that is alsothe second force applying portion) nearest to the seam 2830 in theopposite direction. In addition, the imaginary arc connecting the seam2830 and the contact point 2831B in the rotation direction C (theopposite direction to the direction in which force is received)corresponds to the first imaginary arc according to the presentinvention. Specifically, a portion of the metal plate cylindrical shaft283 at the contact point 2831B when connecting the seam 2830 and thecontact point 2831B in the rotation direction C corresponds to the drivetransmitting portion (the first force receiving portion that is also thefirst force applying portion) nearest to the seam 2830 in the rotationdirection C.

In other words, since only one drive transmission point 2831B isprovided in the present embodiment, the drive transmitting portionnearest to the seam 2830 in the opposite direction to the rotationdirection C and the drive transmitting portion nearest to the seam 2830in the rotation direction C are the same drive transmission point.Therefore, when ∠B_(ccw)OP denotes a central angle from the point P tothe point B in the opposite direction to the rotation direction C and∠B_(cw)OP denotes a central angle from the point P to the point B in therotation direction C, the recessed groove 2831 is arranged so that∠B_(ccw)OP becomes larger than ∠B_(cw)OP.

FIGS. 26A to 26C are schematic diagrams showing arrangements of therecessed groove 2831 and the seam 2830 in the form of a comparisonbetween the arrangement according to the present embodiment andarrangements according to comparative examples. FIG. 26A is a diagram ina case (the present embodiment) in which the drive receiving portion isarranged with respect to the metal plate cylindrical shaft 283 asdescribed above so as to satisfy ∠B_(ccw)OP>∠B_(cw)OP. FIG. 26B is adiagram in a case (a seventh comparative example) which, conversely,satisfies ∠B_(ccw)OP<∠B_(cw)OP, and FIG. 26C is a diagram in a case (aneighth comparative example) in which the recessed groove 2831 isprovided on the seam 2830 (provided at overlapping positions in thecircumferential direction as viewed in the axial direction).

In a similar manner to the first embodiment, when the metal platecylindrical shaft 283 transmits a driving force to the pin 261, themetal plate cylindrical shaft 283 receives a reaction force at the drivetransmitting portion point B. When the metal plate cylindrical shaft 283transmits a driving force and a force is applied at the contact point B,in the arrangement shown in FIG. 26C, the force is applied in adirection that causes the seam 2830 to open. In the arrangement shown inFIG. 26B, since the force acts in a direction that causes the seam 2830to open and in a direction that causes the seam 2830 to deviate in aradial direction, torsion of the shaft may possibly increase.Conversely, in the arrangement shown in FIG. 26A, since a force isapplied in a direction that causes the seam 2830 to close, the seam isprevented from opening. In addition, in the arrangement shown in FIG.26A, although a force is also applied in a direction that causes adeviation of the metal plate cylindrical shaft 283 in the radialdirection in a similar manner to FIG. 26B, due to ends of a metal platecoming into contact with each other at the seam 2830, the force appliedin a direction causing the seam 2830 to close becomes a force thatpushes the ends of the metal plate of the seam 2830 against each other.Accordingly, due to an increase in a friction force between the ends ofthe metal plate of the seam 2830, a deviation of the metal platecylindrical shaft 283 in the radial direction can be suppressed.

Therefore, the present embodiment adopts the configuration shown in FIG.26A in which the seam 2830 is less likely to open and a deviation of themetal plate cylindrical shaft 283 in the radial direction is less likelyto occur. In addition, by arranging the recessed groove 2831 in thismanner, the seam 2830 of the metal plate cylindrical shaft 283 isprevented from opening or deviating and a torsional strength of themetal plate cylindrical shaft 283 is prevented from declining.

As described above, in the metal plate cylindrical shaft 283 that is ametallic drive transmitting member, by configuring a positionalrelationship among the seam 2830 of ends of a metal plate, a drivereceiving portion on a drive input side, and a drive transmittingportion on a drive transmitting side as in the present embodiment,torsional strength of the metal plate cylindrical shaft 83 can beprevented from declining. Therefore, even with a hollow-structurecylindrical shaft created by forming a metal plate into a cylindricalshape, an inexpensive and readily workable drive transmitting mechanism(a drive transmitting apparatus) with high drive transmission accuracycan be provided without having to provide a shape requiring specialmachining considerations and without having to apply welding or adhesionto the seam 2830.

The drive transmitting apparatus according to the present inventionincludes:

a first member that drives;

a second member that drives due to a driving force of the first member;and

a cylindrical shaft that rotates in order to transmit the driving forceof the first member to the second member, the cylindrical shaftincluding a pair of circumferential ends that oppose or abut with eachother in a circumferential direction from one end to another end in anaxial direction as a seam, a force-receiving notched portion that isrecessed in the axial direction on an approximately annular end surfaceat one end in the axial direction, and a force-applying notched portionthat is recessed in the axial direction on an approximately annular endsurface at another end in the axial direction, the cylindrical shaftengaging with the first member in the force-receiving notched portionand receiving the driving force of the first member in thecircumferential direction, and the cylindrical shaft engaging with thesecond member in the force-applying notched portion and causing thedriving force to act on the second member in the circumferentialdirection, wherein

when viewed in the axial direction,

the seam, the force-receiving notched portion, and the force-applyingnotched portion are at different positions in the circumferentialdirection,

a central angle of an imaginary arc connecting the seam and a firstforce receiving portion being a force receiving portion which receivesthe driving force in the circumferential direction at theforce-receiving notched portion and which is nearest to the seam in anopposite direction to a rotation direction of the cylindrical shaft fromthe seam to the first force-receiving portion in the opposite directionand having as a center thereof the rotational center being smaller thana central angle of an imaginary arc connecting the seam and a secondforce receiving portion which is the force receiving portion and whichis nearest to the seam in the rotation direction from the seam to thesecond force receiving portion in the rotation direction and having as acenter thereof the rotational center, and

a central angle of an imaginary arc connecting the seam and a firstforce applying portion being a force applying portion which causes thedriving force to act on the second member at the force-applying notchedportion and which is nearest to the seam in the rotation direction ofthe cylindrical shaft from the seam to the first force-applying portionin the rotation direction and having as a center thereof the rotationalcenter being smaller than a central angle of an imaginary arc connectingthe seam and a second force applying portion which is the force applyingportion and which is nearest to the seam in the opposite direction tothe rotation direction from the seam to the second force applyingportion in the rotation direction and having as a center thereof therotational center.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2016-206762, filed on Oct. 21, 2016, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A drive transmitting apparatus, comprising: afirst member; a second member that drives due to a driving force of thefirst member; and a cylindrical shaft that rotates in order to transmitthe driving force of the first member to the second member, thecylindrical shaft including a pair of circumferential ends that opposeor abut with each other in a circumferential direction from one end toanother end in an axial direction as a seam and a notched portion thatis recessed in the axial direction on an approximately annular endsurface at an end in the axial direction, and the cylindrical shaftreceiving a force in the circumferential direction at the notchedportion, wherein when viewed in the axial direction, the pair ofcircumferential ends and the notched portion are at different positionsin the circumferential direction.
 2. The drive transmitting apparatusaccording to claim 1, wherein the notched portion includes, as forcereceiving portions that receive the force in the circumferentialdirection, a first force receiving portion that is nearest to the pairof circumferential ends in an opposite direction to a direction, inwhich the force is received, and a second force receiving portion thatis nearest to the pair of circumferential ends in the direction, inwhich the force is received, and when a first central angle denotes acentral angle of a first imaginary arc, which connects the pair ofcircumferential ends and the first force receiving portion in theopposite direction from the pair of circumferential ends to the firstforce receiving portion, and which has as a center thereof a rotationalcenter of the cylindrical shaft, and when a second central angle denotesa central angle of a second imaginary arc, which connects the pair ofcircumferential ends and the second force receiving portion in thedirection in which the force is received from the pair ofcircumferential ends to the second force receiving portion, and whichhas as a center thereof the rotational center, the first central angleis smaller than the second central angle.
 3. The drive transmittingapparatus according to claim 2, wherein the cylindrical shaft has aplurality of notched portions at at least one end in the axialdirection, the plurality of notched portions at least includes a firstnotched portion provided at a position near to the pair ofcircumferential ends in the opposite direction and a second notchedportion provided at a position near to the pair of circumferential endsin the direction in which the force is received, the first forcereceiving portion is the force receiving portion in the first notchedportion, and the second force receiving portion is the force receivingportion in the second notched portion.
 4. The drive transmittingapparatus according to claim 3, wherein the second notched portion is ata position farther from the pair of circumferential ends in thecircumferential direction than the first notched portion.
 5. The drivetransmitting apparatus according to claim 2, wherein the cylindricalshaft has a single notched portion at at least one end in the axialdirection, and the first force receiving portion and the second forcereceiving portion are the same force receiving portion in the singlenotched portion.
 6. The drive transmitting apparatus according to claim3, wherein the first central angle is an acute angle.
 7. The drivetransmitting apparatus according to claim 3, wherein the second centralangle is an approximately right angle or an obtuse angle.
 8. The drivetransmitting apparatus according to claim 2, wherein the cylindricalshaft engages with the first member at the notched portion, rotates byreceiving a driving force of the first member in a circumferentialdirection at the notched portion, and the force that the notched portionreceives in the circumferential direction is a force received from thefirst member.
 9. The drive transmitting apparatus according to claim 2,wherein the cylindrical shaft engages with the second member at thenotched portion, and by rotating due to a driving force of the firstmember, causes the driving force to act on the second member in thecircumferential direction at the notched portion, thereby driving thesecond member, and the force that the notched portion receives in thecircumferential direction is a reaction force received from the secondmember when driving the second member.
 10. A drive transmittingapparatus, comprising: a first member; a second member that drives dueto a driving force of the first member; and a cylindrical shaft thatrotates in order to transmit the driving force of the first member tothe second member, the cylindrical shaft including a pair ofcircumferential ends that oppose or abut with each other in acircumferential direction from one end to another end in an axialdirection as a seam, and a notched portion that is recessed in the axialdirection on an approximately annular end surface at an end in the axialdirection, and the cylindrical shaft engaging with the first member inthe notched portion and receiving the driving force of the first memberin the circumferential direction, wherein when viewed in the axialdirection, the pair of circumferential ends and the notched portion areat different positions in the circumferential direction.
 11. The drivetransmitting apparatus according to claim 10, wherein the notchedportion includes, as force receiving portions that receive the drivingforce in the circumferential direction, a first force receiving portionthat is nearest to the pair of circumferential ends in an oppositedirection to a rotation direction of the cylindrical shaft and a secondforce receiving portion that is nearest to the pair of circumferentialends in the rotation direction, and when a first central angle denotes acentral angle of an imaginary arc, which connects the pair ofcircumferential ends and the first force receiving portion in theopposite direction from the pair of circumferential ends to the firstforce receiving portion, and which has as a center thereof therotational center, and when a second central angle denotes a centralangle of an imaginary arc, which connects the pair of circumferentialends and the second force receiving portion in the rotation directionfrom the pair of circumferential ends to the second force receivingportion, and which has as a center thereof the rotational center, thefirst central angle is smaller than the second central angle.
 12. Adrive transmitting apparatus, comprising: a first member that drives; asecond member that drives due to a driving force of the first member;and a cylindrical shaft that rotates in order to transmit the drivingforce of the first member to the second member, the cylindrical shaftincluding a pair of circumferential ends that oppose or abut with eachother in a circumferential direction from one end to another end in anaxial direction as a seam, and a notched portion that is recessed in theaxial direction on an approximately annular end surface at an end in theaxial direction, and the cylindrical shaft engaging with the secondmember in the notched portion and causing the driving force to act onthe second member in the circumferential direction, wherein when viewedin the axial direction, the pair of circumferential ends and the notchedportion are at different positions in the circumferential direction, thenotched portion includes, as force applying portions that cause thedriving force to act on the second member, a first force applyingportion that is nearest to the pair of circumferential ends in arotation direction of the cylindrical shaft and a second force applyingportion that is nearest to the pair of circumferential ends in anopposite direction to the rotation direction, and when a first centralangle denotes a central angle of an imaginary arc, which connects thepair of circumferential ends and the first force applying portion in therotation direction from the pair of circumferential ends to the firstforce applying portion, and which has as a center thereof the rotationalcenter, and when a second central angle denotes a central angle of animaginary arc, which connects the pair of circumferential ends and thesecond force applying portion in the opposite direction from the pair ofcircumferential ends to the second force applying portion, and which hasas a center thereof the rotational center, the first central angle issmaller than the second central angle.
 13. The drive transmittingapparatus according to claim 1, wherein at the pair of circumferentialends, at least one protruded portion which protrudes in thecircumferential direction and which is provided on one of the pair ofcircumferential ends, and at least one recessed portion which isrecessed in the circumferential direction and which is provided on theother circumferential end, fit with each other.
 14. The drivetransmitting apparatus according to claim 13, wherein the protrudedportion has a tapered shape in which the closer to a tip, the narrower awidth in the axial direction, and the recessed portion has a flaredshape in which the closer to an opening side, the wider a width in theaxial direction.
 15. The drive transmitting apparatus according to claim1, wherein the cylindrical shaft is made of metal.
 16. The drivetransmitting apparatus according to claim 1, wherein the cylindricalshaft is a press-worked article.
 17. An image forming apparatus,comprising: the drive transmitting apparatus according to claim 1; andan image forming portion that forms an image on a recording material byusing a driving force transmitted by the drive transmitting apparatus.